Mixed Solid-state Fermentation Research Articles

Optimization of culture conditions for xylanase production by mixed fungal fermentation: Effects on pretreated maize cobs

The use of microorganisms for xylanase production plays important role in the bioconversion of lignocelluloses and also required in huge amount for industrial level application. This necessitates the need to select potent microorganisms for xylanase production, followed by optimization of media components for enhanced production. The effects of altering cultural fermentation conditions on the xylanase production ability in maize cobs were investigated. A consortium of four fungi; Lenzites betulina, Trichoderma reesei, Lachnocladium specie and Aspergillus niger were used to carry out single and mixed solid-state fermentation on NaOH pretreated maize cobs. Optimization of fermentation factors were carried out from ten groups of individual and co-fermented fungal combinations. L. flavidum was found to be the most effective xylanase producer with optimal conditions at pH of 5.5, moisture 75%, inoculum concentration at 5-6 x 103 spores/ml, incubation period of 7-9 days and 1% peptone as the best nitrogen media supplement. Variation to different degrees in the degradation of the maize cobs were observed. A 10% decrease in cellulose was observed with co- cultures of T. reesei and A. niger and a 15% decrease in the hemicellulose fraction. The biotechnological potential of corn cobs has been enhanced by the screening and optimizing the culture conditions.

Release characteristic of bound polyphenols from tea residues insoluble dietary fiber by mixed solid-state fermentation with cellulose degrading strains CZ-6 and CZ-7

The purpose of this work was to investigate the release characteristic of bound polyphenols (BP) from tea residues insoluble dietary fiber (IDF) by mixed solid-state fermentation (SSF) with cellulose degrading strains CZ-6 and CZ-7. The results implied that cellulase, β-glucosidase and filter paper lyase activities were strongly correlated with the BP content. The scanning electron microscop and fourier transform infrared spectroscopy manifested that the cellulose network of the IDF was decomposed and dissolve, forming more loose fibrous structure. Additionally, 28 polyphenols components were detected and their biotransformation pathways were preliminary speculated. Moreover, the BP obtained by mixed SSF produced prominent inhibitory activities against α-glucosidase and α-amylase, as well as exhibited significant scavenging effects on DPPH•, ABTS+• free radicals and ferric reducing antioxidant power. These findings could further promote the utilization of BP from agricultural by-products in a more natural and economical method, CZ-6 and CZ-7 strains provide a new approach to expound the release and conversion of BP.

Effect of Soluble Dietary Fiber of Navel Orange Peel Prepared by Mixed Solid-State Fermentation on the Quality of Jelly.

The aim of this work was to prepare soluble dietary fibers (SDFs) from insoluble dietary fiber of navel orange peel (NOP-IDF) by mixed solid-state fermentation (M-SDF) and to investigate the influence of fermentation modification on the structural and functional characteristics of SDF in comparison with untreated soluble dietary fiber (U-SDF) of NOP-IDF. Based on this, the contribution of two kinds of SDF to the texture and microstructure of jelly was further examined. The analysis of scanning electron microscopy indicated that M-SDF exhibited a loose structure. The analysis of scanning electron microscopy indicated that M-SDF exhibited a loose structure. In addition, M-SDF exhibited increased molecular weight and elevated thermal stability, and had significantly higher relative crystallinity than U-SDF. Fermentation modified the monosaccharide composition and ratio of SDF, as compared to U-SDF. The above results pointed out that the mixed solid-state fermentation contributed to alteration of the SDF structure. Furthermore, the water holding capacity and oil holding capacity of M-SDF were 5.68 ± 0.36 g/g and 5.04 ± 0.04 g/g, which were about six times and two times of U-SDF, respectively. Notably, the cholesterol adsorption capacity of M-SDF was highest at pH 7.0 (12.88 ± 0.15 g/g) and simultaneously exhibited better glucose adsorption capacity. In addition, jellies containing M-SDF exhibited a higher hardness of 751.15 than U-SDF, as well as better gumminess and chewiness. At the same time, the jelly added with M-SDF performed a homogeneous porous mesh structure, which contributed to keeping the texture of the jelly. In general, M-SDF displayed much excellent structural and functional properties, which could be utilized to develop functional food.

Mixed Solid-State Fermentation of Okara and Copra Meal by Probiotics with Non-Starch Polysaccharide Enzymes and Its Effects on the Growth Performance and Ileal Microbiota in Broilers

With the global shortage of feed ingredients, the use of agricultural by-products has become an alternative to animal feed. Okara, a by-product of soymilk and tofu processing, is high in nutrients but contains non-starch polysaccharides (NSP) and has a high-water content, which are disadvantages in animal feed. Herein, we mixed okara and copra meal (CM) with probiotics (Lactobacillus species and Clostridium butyricum) and NSP enzymes (NSPases) for solid-state fermentation (SSF) to enhance okara feed value; the optimal parameters of fermented okara and CM (FOCM) and their effects on broiler growth performance and ileal microbiota were investigated. The result showed that FOCM in combination with NSPases and probiotics at 55% of the initial moisture content and 60 h fermentation time at 37 °C were able to degrade NSP and reduce sugar content. After fermentation, the total viable counts, lactic acid, and butyric acid contents in the FOCM were 8.6 log CFU/g, 3.7%, and 17.15%, respectively. During the fifth week of the feeding period and over the whole feeding period, broilers fed with 1.25% and 2.5% FOCM had a better feed conversion ratio (p < 0.05); both groups increased the duodenal villus length (p < 0.05). Further microbiome analysis suggested that FOCM significantly increased the abundance of the phylum Firmicutes and reduced the abundance of Escherichia-Shigella in the ileal content (p < 0.05). Collectively, supplementation of probiotics and enzymes during SSF was found to be effective in enhancing the nutritional value of FOCM. Moreover, dietary supplementation of FOCM improved the broiler feed conversion ratio, gut morphology, and ileal microbiota.

Release characteristic and mechanism of bound polyphenols from insoluble dietary fiber of navel orange peel via mixed solid-state fermentation with Trichoderma reesei and Aspergillus niger

Dietary fiber (DF) is a carrier of abundant bound polyphenols (BP). The present work was to investigate the release characteristic and mechanism of BP from the insoluble dietary fiber of navel orange peel (NOP-IDF) by mixed solid-state fermentation (SSF) with Trichoderma reesei and Aspergillus niger. The optimized fermentation conditions were set as follows: inoculation ratio of T. reesei to A. niger 3:1, delayed inoculation time 28 h and initial pH 6.5. The compositions of BP were identified and quantified by UPLC-ESI-QTOF-MS/MS and HPLC-ESI-QQQ-MS/MS, then the biotransformation pathways were partially speculated. Moreover, cellulase, xylanase and β-glucosidase activities were strongly correlated with the BP content. The SEM showed the cell wall and the crystalline structure of the NOP-IDF was effectively decomposed. Furthermore, mixed SSF significantly enhanced in vitro antioxidant activities of BP. In summary, our study demonstrated that mixed SSF was a feasible method for the BP release.

Mixed solid-state fermentation for releasing bound polyphenols from insoluble dietary fiber in carrots via Trichoderma viride and Aspergillus niger.

This study aimed to explore the release mechanism of bound polyphenols (BP) from the insoluble dietary fiber (IDF) in carrots via mixed solid-state fermentation (MSF) using Trichoderma viride and Aspergillus niger. The results indicated that BP released by MSF (80.8759 mg GAE per 10 g DW) was significantly higher than that by alkaline hydrolysis. In addition, 17 polyphenols were detected and their biotransformation pathways were proposed. Quantitative analysis showed that MSF released numerous p-coumaric and organic acids, which led to both an enhancement in α-amylase inhibitory activity and elevated antioxidant enzyme activity in Caenorhabditis elegans (C. elegans). Furthermore, the dynamic changes in the carbohydrate-hydrolyzing enzymes and the structural characteristics indicated that the destruction of hemicellulose, the deposition of lignin and the secretion of xylanase were vital for the release of BP. Overall, this study demonstrated that MSF is beneficial for the release of BP from IDF, which could provide new insight into the utilization of agricultural byproducts in a more natural and economical way.

Co-fermentation of lentils using lactic acid bacteria and Bacillus subtilis natto increases functional and antioxidant components.

We identified lentil products with both nutritional value and antioxidant capacity by studying the changes of probiotics and functional substances during single fermentation with lactic acid bacteria (LAB) or co-fermentation using LAB and Bacillus subtilis natto. After fermentation, the best growth of LAB was observed in anaerobic solid-state co-fermentation, whereby the viable counts of Lactobacillus plantarum TK9 and Lactobacillus paracasei TK1501 reached 2.77 × 109 and 2.78 × 109 CFU/g, respectively. Furthermore, the total phenol and genistin content produced by the two mixed groups, respectively, increased by 0.52- and 0.66-fold, as well as 0.63- and 0.64-fold, compared with unfermented samples. Similarly, the free amino acid content increased by 0.53- and 0.49-fold, respectively. The 50% inhibitory concentrations for the radical-scavenging against 1,1-diphenyl-2-picrylhydrazyl and α-glucosidase inhibitory activity were lower following anaerobic co-fermentation. Consistently, products of anaerobic mixed solid-state fermentation had higher oxygen radical absorbance capacity. Therefore, anaerobic solid-state co-fermentation of lentils using B. subtilis natto may promote the multiplication of LAB and enhance the antioxidant activity of fermented lentil products. PRACTICAL APPLICATION: Simple and efficient food handling is more suitable for industrial production. Co-fermentation is a good method to optimize the fermentation process. Co-culture technology has high potential in terms of functionality and antioxidant capacity.

Optimization of Mixed Solid-state Fermentation of Soybean Meal by Lactobacillus Species and Clostridium butyricum.

Soybean meal is the main vegetable protein source in animal feed. Soybean meal contains several anti-nutritional factors, which directly affect digestion and absorption of soy protein, thereby reducing growth performance and value in animals. Fermented soybean meal is rich in probiotics and functional metabolites, which facilitates soybean protein digestion, absorption and utilization in piglets. However, the mixed solid-state fermentation (SSF) conditions of soybean meal remain to be optimized. In this study, we investigated the optimal parameters for SSF of soybean meal by Lactobacillus species and Clostridium butyricum. The results showed that two days of fermentation was sufficient to increase the viable count of bacteria, lactic acid levels and degradation of soybean protein in fermented soybean meal at the initial moisture content of 50%. The pH value, lowering sugar content and oligosaccharides in fermented soybean meal, was significantly reduced at the initial moisture content of 50% after two days of fermentation. Furthermore, the exogenous proteases used in combination with probiotics supplementation were further able to enhance the viable count of bacteria, degradation of soybean protein and lactic acid level in the fermented soybean meal. In addition, the pH value and sugar content in fermented soybean meal were considerably reduced in the presence of both proteases and probiotics. Furthermore, the fermented soybean meal also showed antibacterial activity against Staphylococcus aureus and Escherichia coli. These results together suggest that supplementation of both proteases and probiotics in SSF improves the nutritional value of fermented soybean meal and this is suitable as a protein source in animal feed.

Consolidated bioprocess for bioethanol production with alkali-pretreated sugarcane bagasse

A consolidated bioprocess integrating enzyme production, saccharification and fermentation was applied for bioethanol production. Mixed solid-state fermentation of alkali-pretreated sugarcane bagasse (SCB) supplemented with wheat bran (WB) to produce a compound enzyme for saccharification by Trichoderma and Penicillium was carried out, and at 72h, the obtained sugars concentration was 20.190g/L. Then the mixture was further converted to ethanol by inoculating Saccharomyces cerevisiae. After 24h, the maximum ethanol concentration 5.825g/L (40.84% of theoretical yield) was achieved. At 144h, the produced β-glucosidase activity and fungal biomass were 0.483IU/mL and 0.204g/g, respectively. The consolidated bioprocess avoided enzyme preparation, saved much water/energy consumption and reduced equipment investment, which indicated that it might be an effective approach for the economic production of bioethanol.

Enhanced viability of Lactobacillus reuteri for probiotics production in mixed solid-state fermentation in the presence of Bacillus subtilis

In order to develop a multi-microbe probiotic preparation of Lactobacillus reuteri G8-5 and Bacillus subtilis MA139 in solid-state fermentation, a series of parameters were optimized sequentially in shake flask culture. The effect of supplementation of B. subtilis MA139 as starters on the viability of L. reuteri G8-5 was also explored. The results showed that the optimized process was as follows: water content, 50 %; initial pH of diluted molasses, 6.5; inocula volume, 2 %; flask dry contents, 30∼35 g/250 g without sterilization; and fermentation time, 2 days. The multi-microbial preparations finally provided the maximum concentration of Lactobacillus of about 9.01 ± 0.15 log CFU/g and spores of Bacillus of about 10.30 ± 0.08 log CFU/g. Compared with pure fermentation of L. reuteri G8-5, significantly high viable cells, low value of pH, and reducing sugar in solid substrates were achieved in mixed fermentation in the presence of B. subtilis MA139 (P < 0.05). Meanwhile, the mixed fermentation showed the significantly higher antimicrobial activity against E. coli K88 (P < 0.05). Based on the overall results, the optimized process enhanced the production of multi-microbe probiotics in solid-state fermentation with low cost. Moreover, the viability of L. reuteri G8-5 could be significantly enhanced in the presence of B. subtilis MA139 in solid-state fermentation, which favored the production of probiotics for animal use.

Strategy development for therapeutic protein production by Pichia pastoris: human growth hormone

A consolidated bioprocess integrating enzyme production, saccharification and fermentation was applied for bioethanol production. Mixed solid-state fermentation of alkali-pretreated sugarcane bagasse (SCB) supplemented with wheat bran (WB) to produce a compound enzyme for saccharification by Trichoderma and Penicillium was carried out, and at 72 h, the obtained sugars concentration was 20.190 g/L. Then the mixture was further converted to ethanol by inoculating Saccharomyces cerevisiae. After 24 h, the maximum ethanol concentration 5.825 g/L (40.84% of theoretical yield) was achieved. At 144 h, the produced β-glucosidase activity and fungal biomass were 0.483 IU/mL and 0.204 g/g, respectively. The consolidated bioprocess avoided enzyme preparation, saved much water/energy consumption and reduced equipment investment, which indicated that it might be an effective approach for the economic production of bioethanol.

Study on Thermodynamics and Adsorption kinetics of Purified endoglucanase (CMCase) from Penicillium notatum NCIM NO-923 produced under mixed solid-state fermentation of waste cabbage and Bagasse

Study on Thermodynamics and Adsorption kinetics of Purified endoglucanase (CMCase) from Penicillium notatum NCIM NO-923 produced under mixed solid-state fermentation of waste cabbage and Bagasse

Study on thermodynamics and adsorption kinetics of purified endoglucanase (CMCase) from Penicillium notatum NCIM NO-923 produced under mixed solid-state fermentation of waste cabbage and bagasse.

In the current study, one thermostable endoglucanase was purified from Penicillium notatum NCIM NO-923 through mixed solid state fermentation of waste cabbage and bagasse. The molecular weight of the purified enzyme was 55kDa as determined by SDS polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme had low activation energy (Ea) of 36.39KJ mol-1 for carboxymethyl cellulose hydrolysis and the enthalpy and entropy for irreversible inactivation was 87 kJ mol −1 and 59.3 J mol −1 K−1 respectively. The enzyme was quite thermostable with a Tm value of 62.2°C. The pKa1 and pKa2 of ionizable groups of the active sites were 2.5 and 5.3 respectively. Apparent Km, Vmax and Kcat of the enzyme were found to be 5.2 mg mL-1, 80 U/gds and 322.4 sec-1 respectively. The enzyme showed about 1.4 fold increased activity in presence of 10mM MgSO4. Adsorption of endoglucanase on Avicel at wide pH range was studied at different temperatures. Langmuir type adsorption isotherm at 10°C showed maximum adsorption strength of enzyme at pH 3.0, which was in a range of optimum pH of the enzyme.

Bed moisture estimation by monitoring of air stream temperature rise in packed-bed solid-state fermentation

We develop a method for predicting the moisture content of the fermenting solids in an intermittently mixed packed-bed bioreactor on the basis of measurements of the inlet and outlet gas stream temperatures and the assumption that both the gas streams are saturated with water vapor. This method can be used to estimate when an intermittently mixed packed bed should be mixed and how much water should be added during the mixing event. The predictions were experimentally verified for the growth of Aspergillus niger on wheat bran in a thin packed bed. We show that the application of a controller based on our estimation method would have led to adequate moisture control, with significant errors in moisture content prediction only occurring after the last mixing and water-addition event. Our method therefore represents a simple and practical method that can be incorporated into control schemes for intermittently mixed solid-state fermentation bioreactors with forced aeration.